Response of ultrathin metal films to ultrafast laser irradiation: A comparative molecular-dynamics study

Using molecular-dynamics computer simulation, we study the materials processes in ultrathin metal films induced by ultrafast laser irradiation. We investigate four different metals (Al, Cu, Ti, W), which vary widely in their cohesive energy, melting temperature, bulk modulus, and crystal structure. Despite these variations, we find that the same materials processes are induced in these films: With increasing laser fluence, the film melts, voids are formed, the film tears (spallation), and finally fragments to form a multitude of clusters. When the energy transfer starting the process is scaled to the cohesive energy of the material, the thresholds of these processes adopt similar – but not identical – values.